Oprah Winfrey is a force, both on screen and off. The media mogul has everybody buzzing with her new acting role in HBO's The Immortal Life of Henrietta Lacks. In the film, Winfrey plays Deborah Lacks, the daughter of the woman whose cells revolutionized medical treatment. It's a role she was intimidated to do.

"I've done five movies in my life," Winfrey told us. "So my repertoire is very small. Every time I'm on stage I just feel like everybody here knows more than I do, so you have to then hand yourself over to somebody who knows what they're doing, so that's what I did."

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"It's incredibly humbling to hear that from her. Look, I was intimidated by her obviously," Byrne told E! News. "She had a big undertaking physically and emotionally it was really without vanity this performance, it's not by any means a glamorous part and she just went there."

Hamilton's Renee Elise Goldsberry plays Henrietta Lacks, Winfrey's mother in the film, but the two never share scenes.

"That's right, I actually did not get to film scenes with her, which makes me, I think, more objective. I think when I tell people she's absolutely brilliant in this film you have to believe me because I'm not remembering something that happened on set. I'm really just watching this performance and I'm weeping at the end of this film watching the journey she takes as Deborah Lacks," she told us. "It's absolutely stunning."

Goldsberry confirmed what everybody has long assumed: Winfrey is the real deal.

"She's just filled with light," she told us.

Click play on the video above for more from the cast of The Immortal Life of Henrietta Lacks.

The Immortal Life of Henrietta Lacks airs Saturday, April 22 at 8 p.m. on HBO.